How old is this flag?

As for books, there are not many.
The best is probably Grace Cooper's "13-Star Flags: Keys to Identification"
published by the Smithsonian back in 1974 (I think it was). Grace went into very
minute detail about fabrics and thread and techniques used at various times for
US Flags. Probably much of this material applies to Canadian and European flags
as well.

The cheap hand-wavers prior to about 1940 were made of glazed
cotton and printed, by silk screen at that time and by the press- or clamp-dying
method c.1850 to 1900 or so. Dates for this stuff are pretty hard to pin down. I
have many US Patents for the equipment for making these. From the 14th century
(and probably earlier) nautical flags were made of wool bunting. This didn't
change much until the Second World War brought us the invention of Nylon and
Rayon as flag fabrics. Polyester bunting came into use about the late 1970s or
so. Cotton bunting came into common use following the American Civil War
although there are some older flags that used this material. Cotton bunting is
not heavy at all, it is usually pretty light in weight or (for more decorative
items) medium in weight.Dave Martucci, 13 March 2013